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The present invention relates to a machine for bending tubes in series and at a high rate.
There are already known many devices allowing bending or curving of tubes, which consist mostly of hand tools, whether or not electrically operated, namely used by professionals of the building industry to bend copper tubes, with a view to carry out sanitary installations.
These devices include a radius block having the desired radius of curvature and a backing block capable of being moved, coaxially to said radius block, at the periphery of the latter, thus driving the tube to be bent, which is clamped between said radius block and said backing block, so as to wind it onto said radius block.
A tube cannot be curved or bent in the same ways as a wire, since, because of its axial conduit, a tube is likely to be flattened. Therefore, the radius block and the backing block each include a groove with a cross-section having the shape of an arch of a circle the radius of curvature of which corresponds to the diameter of the tube to be bent.
As a rule, the backing block is in the form of a movable block capable of pivoting to a limited extent and in which the groove is longitudinally provided for, or of a grooved rail-wheel mounted so as to be capable of freely rotating. The bending operation is performed while the tube is into contact with the bottoms of both grooves.
It should be noted that the more the grooves are surrounding, i.e. deep, with a maximum depth equal to the radius of the tube to be bent, the lesser the tube is likely to be flattened.
The tube is thus held laterally by the grooves of the radius block and the backing block, so that, in order to release it laterally from the tool, to remove it and to perform in the latter a second bending in another direction, the tool is provided with means allowing, in addition, replacing the radius block by another one with a different radius of curvature and/or suited for a tube having another diameter.
In order to allow releasing the tube, the bending devices are provided with radius blocks having a cut-off edge, in order to allow releasing the tube from the groove of the backing block. This is the case, e.g. with the machine of GB 1,298,666, which is intended for bending tubes into a U-shape by simultaneously performing two right-angle bends, each one on a backing block. It should be noted that, in order to allow releasing the tube, both backing blocks each include two cut-off edges.
It should also be noted that the machine object of that document is not intended for the same purpose as that of the present invention and that it could in no way perform the same bending operations.
The present invention indeed relates in particular to machines that allows performing the bending of tubes in series and at a high rate, these tubes namely serving for manufacturing frames. These machines include means for supplying the tube, which a bending head provided with bending tools movable with respect to each other is supplied with.
However, these machines are in particular for bending wire; hence, the bending achieved is not always of excellent quality, the tube being in most cases slightly flattened at the level of its bent portion or portions.
Furthermore, with this kind of machine, moving the radius block with respect to the backing block in order to allow releasing the tube laterally represents a loss of time, which is prejudicial for the productivity.
In addition, the use of machines of this kind is limited, since they do not allow e.g. bending a tube at 180xc2x0, then releasing it in order to remove it or to perform a bending operation in another direction.
It should also be noted that it is often necessary to perform two, or even more, bending operations in different directions on a tube, which is achieved by releasing the tube, then re-positioning it after having caused it to perform an axial rotation. With a machine as aforementioned, the axial rotation of the tube is a relative one; indeed, the bending head rotates about the axis of the tube; or, when there is no possibility for a lateral release, which would moreover be performed during a 180xc2x0 bending, said rotation is impossible.
The present invention aims at coping with the various aforementioned drawbacks by providing a tube bending machine that authorizes high working speeds and that namely allows bending the tube at 180xc2x0, without the tube being likely to be flattened.
The machine for bending a tube in series and at a high rate according to the invention includes a bending head comprising a radius block and a backing block that include, on the periphery, a groove with a semicircular cross-section, as well as means allowing driving said backing block in rotation coaxially to said radius block, so as to drive the tube to be bent and to wind it onto said radius block, and it is mainly characterized in that said radius block consists of a disc having a beveled edge arranged along a chord of said disc, and in that it includes means allowing moving said bending head with respect to the axis of the tube, along a path passing through the axes of the radius block and the backing block, as well as means for axially rotating said radius block, independently from the displacement of said backing block.
Through positioning the cut-off edge of the radius block in front of the backing block and through moving the bending head, and hence the radius block and the backing block, with respect to the axis of the tube, it is possible to release the bent tube laterally, by providing a properly sized cut-off edge, i.e. when the distance between the cut-off edge and the edge of the backing block is at least equal to the diameter of said tube.
According to an additional feature of the machine according to the invention, the means allowing moving the bending head with respect to the tube drive the latter according to a rectilinear path.
According to another additional feature of the machine according to the invention, the means allowing moving said bending head with respect to the tube drive the latter according to a curved path.
According to another additional feature of the machine according to the invention, the backing block consists of a rail-wheel.
According to another additional feature of the machine according to the invention, the backing block consists of a pressure block.
According to another additional feature of the machine according to the invention, the means allowing moving the bending head with respect to the tube and the means allowing causing the radius block to rotate axially consist of numerically controlled stepping motors.
According to a preferred embodiment of the machine according to the invention, the bending head is borne by a pivoting arm on which it is movable in rotation coaxially to the radius block, the latter being mounted so as to be movable in axial rotation about the bending head.